The present invention relates to a scroll compressor furnished in an air conditioner, a refrigerator, or the like.
A scroll compressor is one where a fixed scroll and an orbiting scroll are arranged as a pair of spiral walls assembled together, and the orbiting scroll is orbitally rotated with respect to the fixed scroll in order to gradually reduce the volume of a compression chamber formed between the walls and thereby compress the fluid inside the compression chamber.
The compression ratio in the design of the scroll compressor is a ratio of the maximum capacity of the compression chamber (the capacity at a point in time where the wall pairs are combined to form the compression chamber) to the minimum capacity of the compression chamber (the capacity immediately before the wall pairs become disengaged and the compression chamber disappears), and is expressed by the following equation (I):
Vi={A (xcex8suc)xc2x7L}/{A (xcex8top)xc2x7L}=A (xcex8suc)/A (xcex8top) xe2x80x83xe2x80x83(I) 
In equation (I), A(xcex8) is a function representing the cross-sectional area parallel to the orbit plane of the compression chamber for which the volume is changed corresponding to the orbiting angle xcex8 of the orbiting scroll, xcex8suc is the orbit angle of the orbiting scroll for when the compression chamber becomes a maximum volume, xcex8top is the orbit angle of the orbiting scroll for when the compression chamber becomes a minimum volume, and L is the length of the lap (overlap) of the wall pairs.
Conventionally, in order to improve the compression ratio Vi of a scroll compressor, a method was adopted of increasing the winding number for the walls of the two scrolls so that the cross-section area A(xcex8) of the compression chamber at the time of maximum volume was increased. However, with this conventional method of increasing the winding number of the walls, the external shape of the scroll is increased so that the compressor itself is increased in size. Hence there is a problem in that it is difficult to employ this in an air conditioner such as for an automobile where restrictions on size are severe.
In order to solve the above problems, in Japanese Examined Patent Application, Second Publication, No. 60-17956, there is proposed a scroll compressor where spiral shape upper rims of the walls of both the fixed scroll and the orbiting scroll are made of a stepped shape with the central side low and the outer peripheral end side high, and corresponding to the stepped shape of these upper rims, the side faces of end plates of the two scrolls are both are formed stepped with the central side high and the outer peripheral end side low.
The device shown in FIG. 41A is a fixed scroll 150, and comprises an end plate 150a and a wall 150b of a spiral shape upstanding on one side face of the end plate 150a. Furthermore, the device shown in FIG. 41B is an orbiting scroll 151. The orbiting scroll 151 also comprises an end plate 151a and a spiral wall 151b upstanding on one side face of the end plate 151a, similar to that of the fixed scroll 150.
On the side faces of the end plates 150a and 151a of the fixed scroll 150 and the orbiting scroll 151, there is formed steps 152 at a position xcfx80 radians (rad) from the outer peripheral end of the spirals of the walls 150b and 151b, and these steps have their central sides high and their outer peripheral end sides low. Furthermore, corresponding to the steps 152 of the end plates 150a and 151a, there are formed steps 153 on the spiral shape upper rims of the walls 150b and 151b furnished on the two scrolls 150 and 151, with their central sides low and the outer peripheral end sides high.
In the scroll compressor as described above, the condition where the respective walls 150b and 151b of the fixed scroll 150 and the orbiting scroll 151 are engaged, and a compression chamber P of maximum capacity is formed, is shown in FIG. 42A, and a cross-section along the spiral direction of the compression chamber P, is shown in FIG. 42B. The leftward direction of FIG. 42B is the spiral central side.
As will be understood from FIG. 42B, a lap length L1 on the outer peripheral end side from the step 152 is formed longer than a lap length Ls for the inside. Therefore, compared to the case where the lap lengths are the same, it can be seen that the maximum volume of the compression chamber P becomes larger by the amount that the lap length outside from the step 52 is longer. Consequently, it is possible to improve the design compression ratio even if the winding number of the walls is not increased.
As described above, since the lap length of the compression chamber at the time of maximum capacity is L1 and the lap length of the compression chamber at the time of minimum capacity is Ls, then a design compression ratio Vixe2x80x2 can be expressed by the following equation (II).
Vixe2x80x2={A (xcex8suc)xc2x7L1}/{A (xcex8top)xc2x7Ls}xe2x80x83xe2x80x83(II) 
In equation (II), the lap length L1 of the compression chamber at the time of maximum capacity is larger than the lap length of the compression chamber at the time of minimum capacity so that L1/Ls greater than 1 results. Therefore, it is possible to increase the design compression ratio even if the winding number for the walls is not increased.
Furthermore, Japanese Unexamined Patent Application, First Publication, No. 4-311693 discloses a structure which adopts a stepped shape for the scroll, and there is provided a tip seal on an outer peripheral lap tip, with the, purpose of reducing leakage at the outer peripheral side.
Incidentally, in general in a scroll compressor, since the compression chamber P becomes a higher pressure at the central portion of the scroll, the temperature is higher compared to at the outer peripheral portion. Therefore, the thermal expansion amount for the wall becomes larger at the central portion, so that geometric distortion occurs in the engagement between the fixed scroll 150 and the orbiting scroll 151, with the problem of likelihood in an increase in leakage and a reduction in reliability.
Furthermore, in the conventional scroll compressor, the steps 152 formed on the side faces of the end plates 150a and 151a of the scrolls 150 and 151 are positioned at xcfx80 (rad) from the outer peripheral end of the spiral. Therefore, as will be understood from FIG. 42B, the lap length Ls from the step 152 towards the central portion is shorter than the lap length L1 for the outer peripheral end side, so that even at the time of maximum volume, a sufficiently large volume cannot be obtained.
Moreover, as shown in the cross-sectional view of FIG. 43, the construction is such that a discharge port 154 passing through the end plate 150a is formed in the central portion of the fixed scroll 150 for discharging high pressure fluid inside the compression chamber P. However, since the volume inside this discharge port 154 is comparatively large, there is a problem in that the fluid cannot be discharged smoothly, making it difficult to improve the operating efficiency.
As described above, in relation to where the step 152 is formed on the side face of the end plate 150a of the fixed scroll 150, then for the central portion of the end plate 150a, the thickness becomes comparatively thicker than for the outer peripheral portion bounded by the step 152. Therefore, the length of the discharge port 154 becomes longer, and consequently the volume inside the discharge port 154 becomes comparatively large.
The fluid flowing from the compression chamber P to inside the discharge port 154 causes elastic deformation at a rectangular flat plate discharge valve 155, so that the discharge port 154 is opened, and due to the opening, the fluid flows out towards a discharge cavity (not shown in the figure). However, since the volume of the discharge cavity is large, up until the discharge valve 155 is again closed due to the pressure rise inside the discharge cavity, the fluid has not been sufficiently introduced and thus remains.
Then, the remaining fluid flows in reverse, returning to inside the compression chamber P, and thus raising the pressure of the fluid which is to be compressed next. Obviously, in compressing high pressure fluid extra power must be added compared to when compressing low pressure fluid, that is, the power for rotating the orbiting scroll 151 with respect to the fixed scroll 150 must be increased. Consequently, the motor, being the rotational drive source for the orbiting scroll 151, is subjected to an extra load due to the fluid which flows in reverse from the discharge port 154. Therefore, more electric power is consumed, making it difficult to improve the operating efficiency.
Furthermore, this is not only limited to the device where the step shape is adopted for the scroll as described above, but also in the conventional general scroll compressor, a technique for variably controlling the discharge volume is occasionally adopted. This is because for example in an air-conditioning plant, while performing steady operation, the conveyance of a large amount of refrigerant is not required compared to for example at the time of starting.
In volume control, it is common to adopt a technique for flowing a part of the suction fluid from the high pressure side to the low pressure side, to thereby reduce the discharge volume. However, if a part of the fluid which has been once compressed to a high pressure is reflowed from the high pressure side to the low pressure side, this causes drive source power loss, and is inefficient.
Furthermore, in the scroll compressor which adopts the stepped shape as mentioned above for the scroll, there is a problem in how to maintain the gas tightness when a connecting rim which connects the upper rim of the low position and the upper rim of the high position of the wall bodies against the connecting wall face which connects the deep lower face of the bottom and the shallow lower face of the bottom of the end plate.
For example, in Japanese Examined Patent Application, Second Publication, No. 60-17956, it is disclosed that the shape of a portion being the connecting rim, is formed in a semicircular shape of a radius xcfx80/2, which is smoothly continuous with the two side faces of the spiral shape walls, and the shape of a portion being the connecting wall face, is formed so as to be a semicircle of a radius ro+(xcfx80/2) (ro; orbit radius of the orbiting scroll) with the central point of the adjacent wall as the center.
However, it is known that in order to form such a connecting rim as a semicircular shape which is smoothly continuous with the two side faces of the wall, an extremely high processing technique is required. Therefore processing cost is considerably increased, which becomes an inhibiting factor for mass production.
Furthermore, there is a problem in that it takes time to machine the scroll, and cost is high. Therefore, a scroll compressor is proposed where a step is provided in the scroll wall of either one of the fixed scroll and the orbiting scroll, and a step is provided in the end plate of the other scroll which is to correspond to this (refer to FIG. 8 of Japanese Examined Patent Application, Second Publication, No. 60-17956). In this compressor, the step machining for the wall and the step machining for the end plate are completed at one location for each of the two scrolls, thus realizing high processability.
However, the condition exists where the volume of the two facing compression chambers on either side of the center of the scroll compressor are not equal during the compression process. Therefore, at the time of actual driving, the pressure balance between the two compression chambers is lost, and in the worst case, this can contribute to damage of the internal structure of the compressor.
The present invention takes into consideration the above situation with the object of providing a scroll compressor as hereunder.
(1) A scroll compressor for which the scrolls can be reliably engaged even at the time of thermal expansion, and the compression efficiency can be improved and a high reliability maintained.
(2) A scroll compressor for which a maximum volume for the compression chamber can be sufficiently obtained to enable improvement in the compression ratio.
(3) A scroll compressor in which improvement of the operating efficiency is not prevented by fluid remaining inside the discharge port, thus enabling operating efficiency to be improved.
(4) A scroll compressor where volume control is possible and performance is improved, without producing drive source power loss.
(5) A scroll compressor for which processability of the connecting edge can be increased and a reduction in cost realized, while also maintaining gas tightness between the fixed scroll and the orbiting scroll.
(6) A scroll compressor for which time and cost necessary in machining of the scrolls can be reduced, and which can be safely driven.
The first object of the present invention is to provide a scroll compressor which is furnished with a fixed scroll having a spiral wall upstanding on one side face of an end plate, and secured in place, and an orbiting scroll having a spiral wall upstanding on one side face of an end plate, and supported so as to be orbitally movable while being prevented from rotation, with pairs of the walls engaged with each other, and provided with a stepped shape on one side face of at least one of the end plates of the fixed scroll and the orbiting scroll, having a high part with a height thereof which is high at a central side in a spiral direction, a low part with a height thereof which is low at an outer peripheral end side, and a step which constitutes a border of these high and low parts, and an upper rim of the wall of at least one of the fixed scroll and the orbiting scroll is divided into a plurality of parts, to give a stepped shape having, corresponding to the parts, a low upper rim where the height of the part is low at a central side in the spiral direction, and a high upper rim where the height of the part is high at an outer peripheral end side, wherein a gap is provided between the end plate and a corresponding upper rim of the wall, and a height of the gap in a height direction of the wall at room temperature is formed higher than a height for a case where the wall is thermally expanded in a height direction of the wall at a time of scroll compressor operation.
When the compressor is driven, the central portion of the scroll becomes a higher temperature, and the amount of thermal expansion of the wall becomes large. In this scroll compressor, since a gap having a height higher than the amount of thermal expansion of the wall is formed, then even if the wall expands, the wall upper rim does not interfere with the facing end plate. Furthermore, it is preferable for the gap to be sufficiently small to the extent that the wall and the end plate do not come into contact (for example, 10 xcexcm to 50 xcexcm).
Furthermore, for the outer peripheral end side along the spiral from the step, the height of the wall is formed high. If the wall is high, the displacement in the height direction due to thermal expansion is large. Furthermore, at the spiral central portion since as mentioned above the high temperature is high, then the thermal expansion amount is large. Consequently, the height of the gap for the central portion side and the outer peripheral end side of the step is determined taking into consideration the temperature and the height condition of the wall.
Moreover, in the scroll compressor, the height of the gap formed on the central side in the spiral direction from the step may be formed higher than the height of the gap formed on the outer peripheral end side from the step.
At the central portion of the scroll, due to the high temperature the amount of thermal expansion of the wall becomes large. Therefore, by making the gap for the central portion side from the step high, interference of the wall and the end plate at the central portion side is prevented. Furthermore, the gap height after thermal expansion can be appropriately formed for either of the central portion side and the outer peripheral end side from the step.
The second object of the present invention is to provide a scroll compressor which is furnished with at fixed scroll having a spiral wall upstanding on one side face of an end plate, and secured in place, and an orbiting scroll having a spiral wall upstanding on one side face of an end plate, and supported so as to be orbitally movable while being prevented from rotation, with pairs of the walls engaged with each other, and provided with a stepped shape on one side face of at least one of the end plates of the fixed scroll and the orbiting scroll, having a high part with a height thereof which is high at a central side in a spiral direction, a low part with a height thereof which is low at an outer peripheral end side, and a step which constitutes a border of these high and low parts, and an upper rim of the wall of at least one of the fixed scroll and the orbiting scroll is divided into a plurality of parts, to give a stepped shape having, corresponding to the parts, a low upper rim where the height of the part is low at a central side in the spiral direction, and a high upper rim where the height of the part is high at an outer peripheral end side, wherein the step is provided at a position which exceeds a pitch angle of xcfx80 (rad) along the spiral of the wall from the outer peripheral end of the wall towards the central portion.
In this scroll compressor, the step provided on the end plate is provided at a position which exceeds a pitch angle of xcfx80 (rad) from the outer peripheral end of the spiral towards the central portion, with the spiral center as a reference. That is, for example, a step 52 shown in FIG. 11 (b) becomes positioned to the left in the figure, and hence the position where the lap length of the compression chamber is L1 at the time of maximum volume becomes larger, so that the maximum volume of the compression chamber can be made even greater.
Furthermore, in the abovementioned scroll compressor, the step may be provided at a position which does not exceed a pitch angle of 2xcfx80+xcfx80/4 (rad) along the spiral of the wall from the outer peripheral end of the wall towards the central portion.
Since the differential pressure of the compression chambers partitioned on the inside and outside by the spiral of the wall becomes larger the closer to the center of the spiral, then in the case where the step is provided close to the center, the fluid inside the compression chamber on the inside from the step is likely to pass through the step and leak to the compression chamber on the outside. Therefore, the step is preferably not provided too close to the center, and is preferably provided at a position which does not exceed the pitch angle of 2xcfx80+xcfx80/4 (rad).
Furthermore, in the abovementioned scroll compressor, the step may be provided within range of a pitch angle of 2xcfx80xc2x1xcfx80/4 (rad) along the spiral of the wall from the outer peripheral end of the wall towards the central portion.
By providing the step in the vicinity of 2xcfx80 (rad) as in this scroll compressor, the maximum volume of the compression chamber can be made sufficiently large, and leakage of the fluid inside the compression chamber caused by the differential pressure can also be prevented.
Furthermore, in the scroll compressor, in the fixed scroll, a discharge port may be formed in a central portion of the end plate, and the step may be provided at a position which exceeds a pitch angle of 2xcfx80 (rad) along the spiral of the wall from the discharge port towards the outer peripheral end side.
In this scroll compressor, in the case where the number of turns of the scroll is sufficient, then by providing the step at a position on the outer peripheral end at least 2xcfx80 (rad) from the position forming the discharge port, that is at a position where the compression chamber including the step does not face the discharge port, the compression chamber including the step does not attain discharge pressure. Consequently, the seal differential pressure between the spiral central portion side and the outer peripheral end side on either side of the step can be kept small.
The third object of the present invention is to provide a scroll compressor which is furnished with a fixed scroll having a spiral wall upstanding on one side face of an end plate, and secured in place, and an orbiting scroll having a spiral wall upstanding on one side face of an end plate, and supported so as to be orbitally movable while being prevented from rotation, with pairs of the walls engaged with each other, and provided with a stepped shape on one side face of at least one of the end plates of the fixed scroll and the orbiting scroll, having a high part with a height thereof which is high at a central side in a spiral direction, a low part with a height thereof which is low at an outer peripheral end side, and a step which constitutes a border of these high and low parts, and an upper rim of the wall of at least one of the fixed scroll and the orbiting scroll is divided into a plurality of parts, to give a stepped shape having, corresponding to the parts, a low upper rim where the height of the part is low at a central side in the spiral direction, and a high upper rim where the height of the part is high at an outer peripheral end side, wherein, on the end plate of the fixed scroll, when viewed facing from a rear face on an opposite side to the face on which the wall is formed, there is formed a concavity positioned further towards a central portion side in the spiral direction than the low part, and in the concavity there is provided a discharge valve for preventing reverse flow of fluid discharging from the front face to the rear face from the discharge port passing through the end plate.
By forming a concavity, the material thickness of the end plate of the fixed scroll at the part in which the discharge port is positioned can be made thin. Furthermore, the discharge port internal volume can be made small and hence fluid remaining here can be reduced.
Moreover, in the above scroll compressor, in the fixed scroll, the step may be provided within range of a pitch angle of 2xcfx80xc2x1xcfx80/4 (rad) along the spiral of the wall from the outer peripheral end towards the central portion, and the concavity, when the end plate is viewed facing from the rear face may be surrounded by the low part from the outer peripheral end up until the step.
As mentioned above, by forming a concavity, the material thickness of the end plate of the fixed scroll at the part in which the discharge port is positioned can be made thin. Furthermore, the discharge port internal volume can be made small and hence fluid remaining here can be reduced.
Moreover, in the above scroll compressor, the discharge valve may be a spiral reed valve having a blocking portion which covers and closes the opening of the discharge port, a resilient portion formed in a spiral shape from the blocking portion, and a securing portion which secures the outer peripheral end of the resilient portion.
By adopting a spiral reed valve being a relatively small valve, the discharge valve can be installed without difficulty even in a narrow concavity.
Moreover, in the above scroll compressor, the discharge valve may be a free valve being a plate having a surface area greater than an opening area of the discharge port, and arranged inside the concavity.
By adopting a free valve, being a relatively small valve, this can be installed without difficulty even in a narrow concavity. For this free valve, it is more preferable to adopt a circular free valve of a disc shape.
Moreover, in the above scroll compressor, with the exception of a portion which covers the opening of the discharge port, a plurality of ventilation areas may be formed radially from the central portion.
Since the free valve has a central portion with a closing area sufficient to cover the opening of the discharge port, the opening is reliably closed when the discharge port is closed. Furthermore, when the fluid is discharged from the discharge port, this can pass through the free valve not only past the outer periphery of the free valve but also through the respective ventilation areas. Therefore, additional resistance on the fluid passing through the free valve can be reduced.
Moreover, in the above scroll compressor, the discharge valve may be a check valve furnished with a valve body which covers the discharge port, and an urging member which urges the valve towards the discharge port.
By adopting a check valve being a relatively small valve, this can be installed without difficulty even in a narrow concavity.
The fourth object of the present invention is to provide a scroll compressor which is furnished with a fixed scroll having a spiral wall upstanding on one side face of an end plate, and secured in place, and an orbiting scroll having a spiral wall upstanding on one side face of an end plate, and supported so as to be orbitally movable while being prevented from rotation, with pairs of the walls engaged with each other, and provided with a stepped shape on one side face of at least one of the end plates of the fixed scroll and the orbiting scroll, having a high part with-a height thereof which is high at a central side in a spiral direction, a low part with a height thereof which is low at an outer peripheral end side, and a step which constitutes a border of these high and low parts, and an upper rim of the wall of at least one of the fixed scroll and the orbiting scroll is divided into a plurality of parts, to give a stepped shape having, corresponding to the parts, a low upper rim where the height of the part is low at a central side in the spiral direction, and a high upper rim where the height of the part is high at an outer peripheral end side, wherein there is provided a plate arranged at the low part of one side face of one of the fixed scroll and the orbiting scroll, which is freely movable in an orbit axis direction of the orbiting scroll, and a pressing device which presses the plate to the upper rim of the other of the wall of either of the fixed scroll and the orbiting scroll.
In this scroll compressor, in the case of performing volume control, the plate is moved freely in the orbit axis direction without operating the pressing device. As a result, in the scroll compressor comprising the fixed scroll and the orbiting scroll, even though the compression chamber tends to develop between the two scroll walls at the part positioned on the outer peripheral end side where the walls are high, the plate is subjected to pressure and moves so that leakage of the fluid occurs, so that the compression chamber moves towards the central side without actually performing compression. Then, when the part positioned on the central side where the walls are low is reached, and the part where the walls are high is passed, a compression chamber with no leakage is finally developed, and compression results. As a result, the volume change of the compression chamber from when compression is started until discharge, is small, and hence the discharge volume is reduced. Moreover, since the compression chamber is not developed until the wall positioned on the central side reaches to the low portion, power for compressing the fluid is not required.
In the case where volume control is not performed, the pressing device is operated so that the plate is pressed to the other wall of either of the fixed scroll or the orbiting scroll. As a result, even if the wall positioned at the outer peripheral end side is a high portion, the plate forms a part of the compression chamber so that the gas tightness is maintained. Therefore, a compression chamber without leaks is developed from the outer peripheral end side up until the central side, to perform compression.
Moreover, in the above scroll compressor, the plate may be a shape which approximately coincides with the low portion when either one of the fixed scroll and the orbiting scroll, is viewed from the surface on which the wall of is formed.
In this scroll compressor, by forming the plate to approximately coincide with the part positioned on the outer peripheral end side, then in the case where volume control is not performed, the gas tightness of the compression chamber which is formed at the part positioned on the outer peripheral end side where the wall is high, is maintained. Furthermore, the plate can be pressed without providing another drive source.
Furthermore, in the abovementioned scroll compressor, the pressing device may be provided with an introduction path which introduces pressure inside a compression chamber with the high part of the scroll on which the plate is arranged formed as one wall, into a space between the low part and the plate.
In this scroll compressor, in the case where volume control is not performed, the pressure inside the compression chamber positioned on the central side in the spiral direction, which is a higher pressure, is introduced to between the plate and the part positioned on the outer peripheral end side, so that the plate is pressed against the pressure inside the compression chamber which is a lower pressure than for the central side, so that the gas tightness of the compression chamber is maintained.
Moreover, in the above scroll compressor, an urging device may be provided which urges the plate in a direction towards the low part.
In this scroll compressor, by providing an urging device, and pulling the plate to a part positioned on the outer peripheral end side, then in the case where the pressing force on the plate by the pressing device for performing volume control is released, a gap occurs between the plate and the opposite wall. As a result, a redundant pressure increase caused by the active fluid leakage at the outer peripheral end side is prevented.
Moreover, in the above scroll compressor, there may be provided a stopper which restricts a movement range of the plate.
In this scroll compressor, by providing a stopper to restrict the movement range of the plate, pressing of the plate too far to the facing wall is prevented. Therefore, deformation of the plate or the occurrence of heat due to excessive friction with the wall is minimized.
The fifth object of the present invention is to provide a scroll compressor which is furnished with a fixed scroll having a spiral wall upstanding on one side face of an end plate, and secured in place, and an orbiting scroll having a spiral wall upstanding on one side face of an end plate, and supported so as to be orbitally movable while being prevented from rotation, with pairs of the walls engaged with each other, and provided with a stepped shape on one side face of at least one of the end plates of the fixed scroll and the orbiting scroll, having a high part with a height thereof which is high at a central side in a spiral direction, a low part with a height thereof which is low at an outer peripheral end side, and a step which constitutes a border of these high and low parts, and an upper rim of the wall of at least one of the fixed scroll and the orbiting scroll is divided into a plurality of parts, to give a stepped shape having, corresponding to the parts, a low upper rim where the height of the part is low at a central side in the spiral direction, and a high upper rim where the height of the part is high at an outer peripheral end side, wherein, for the steps of the respective end plates, a shape of connecting wall faces which connect the high and low parts which are adjacent to each other, is determined by an envelope drawn by an orbit locus of a connecting rim of the upper rims which connects the upper rim of the low part and the upper rim of the high part which are adjacent to each other.
In this scroll compressor, the shape of the connecting wall face is determined by the envelope drawn by the orbit locus of the connecting rim at the time of orbital motion. That is to say, viewing the connecting rim in a plane parallel with the orbit plane, when the center of a circle with the orbit radius as the radius is moved along the connecting rim, the envelope drawn becomes a shape so as to be the outline of the locus of the moved circle on the orbit plane of the connecting wall face. As a result, the gas tightness of the connecting wall face can be maintained irrespective of the shape of the connecting rim. Therefore, if a relatively simple shape is adopted for the connecting rim, processability is improved.
Furthermore, in the abovementioned scroll compressor, the connecting rim may be formed by a plane perpendicular to the spiral direction of the wall.
In this scroll compressor, by forming the connecting rim by a plane which intersects the spiral direction of the wall, then for example in the case of machining the connecting rim, processability can be significantly improved.
Moreover, in the above scroll compressor, a border of the plane and the side face of the wall may be chamfered.
In this scroll compressor, by chamfering the border of the plane and the side face of the wall, the strength near the connecting rim of the wall is maintained, and improvement in machining accuracy achieved.
Furthermore, in the above scroll compressor, a small gap may be provided between the connecting rim on either-one of the fixed scroll and orbiting scroll, and the connecting wall face of the other.
When the scroll compressor is driven, there is a change in the contact pressure due to thermal expansion of the scroll itself. Therefore, in this scroll compressor, by providing a small gap beforehand between the connecting rim and the connecting wall face, then even if the two scrolls thermally expand, the contact pressure does not increase more than necessary, and stabilized drive is achieved.
The sixth object of the present invention is to provide a scroll compressor which is furnished with a fixed scroll having a spiral wall upstanding on one side face of an end plate, and secured in place, and an orbiting scroll having a spiral wall upstanding on one side face of an end plate, and supported so as to be orbitally movable while being prevented from rotation, with pairs of the walls engaged with each other, and an upper rim of the wall furnished on one of either of the fixed scroll and the orbiting scroll is divided into a plurality of parts to give a stepped shape having a low upper rim where the height thereof is low at a central side in the spiral direction, and a high upper rim where the height thereof is high at an outer peripheral end side, and one side face of the end plate furnished on the other of either of the fixed scroll and the orbiting scroll is of a stepped shape having, corresponding to the parts of the upper rims, a high part where the height of the end plate is high at a central side in the spiral direction, and a low part where the height thereof is low at an outer peripheral end side, wherein there is provided a communication passage which communicates between the two compression chambers which are developed by the contact of a connecting rim connecting the low upper rim and the high upper rim, and a connecting wall face connecting the high part and the low part.
Furthermore, in the above scroll compressor, a discharge port may be provided in either one of the fixed scroll and the orbiting scroll.
Moreover, in the abovementioned scroll compressor, opposite ends of the communicating path may be respectively opened at two places where the outside face and the inside face of the walls which develop the compression chamber simultaneously engage.
In the above scroll compressor, in some processes of compression in the two facing compression chambers, the volumes are different. However, in these compression process, the fluid flows through the communication path between the two compression chambers, and hence an imbalance in internal pressure is corrected. As a result, the compressor can be safely driven.
Furthermore, by providing a step only on the wall of the scroll of either one of the fixed scroll and the orbiting scroll, and providing a step only on the end plate of the other scroll which is to correspond to this, processing of the scrolls becomes simpler than heretofore. Hence processability can be improved and the cost required for processing can be reduced.
Moreover, by providing a discharge port in the scroll having no step, the discharge port volume is reduced, and power loss due to reverse flow of the fluid from the discharge port to the compression chamber is suppressed. Hence compression efficiency is improved.
In addition, the seventh object of the present invention is to provide the scroll compressor which is furnished with a fixed scroll having a spiral wall upstanding on one side face of an end plate, and secured in place, and an orbiting scroll having a spiral wall upstanding on one side face of an end plate, and supported so as to be orbitally movable while being prevented from rotation, with pairs of the walls engaged with each other, and upper rims of the respective walls are divided into a plurality of parts to give a stepped shape having a low upper rim where the height thereof is low at a central side in the spiral direction, and a high upper rim where the height thereof is high at an outer peripheral end side, and one side face of each of the end plates is of a stepped shape having, corresponding to the respective parts of the upper rims, a high part where the height of the end plate is high at a central side in the spiral direction, and a low part where the height thereof is low at an outer peripheral end side, wherein a step of the low upper rim and high upper rim of one of either of the fixed scroll and the orbiting scroll is set to be greater than a step of the low upper rim and high upper rim of the other scroll, and a step of the high part and low part of the other scroll is set to be less than a step of the high part and low part of the one scroll, and there is provided a communication passage which communicates between the two compression chambers which are made by the contact of a connecting rim connecting the low upper rim and the high upper rim, and a connecting wall face connecting the high part and the low part.
Furthermore, in the above scroll compressor, a discharge port may be provided in the other scroll for which the step of the low upper rim and high upper rim is set relatively small and the step of the high part and low part is set large.
Moreover, in the abovementioned scroll compressor, opposite ends of the communicating path may be respectively opened at two places where the outside face and the inside face of the walls which develop the compression chamber simultaneously engage.
In the above scroll compressor, in some processes of compression in the two facing compression chambers, the volumes are different. However, in this compression process the fluid flows through the communication path between the two compression chambers, and hence an imbalance in internal pressure is corrected. As a result, the compressor can be safely driven.
Moreover, by providing a discharge port in the scroll with the small step, the discharge port volume is reduced, and power loss due to reverse flow of the fluid from the discharge port to the compression chamber is suppressed. Hence compression efficiency is improved.